1. Field of the Invention
The present invention relates to a process and apparatus for controlling the channeling of parceled goods to be delivered via a delivery conveyor, which includes at least one buffer conveyor, a call-up conveyor, and a channeling conveyor, to free locations on an acceptance conveyor running at a constant speed. The acceptance conveyor and the delivery conveyor are arranged to encompass an angle .alpha., and the delivery conveyor is provided with a parcel measuring device.
2. Discussion of Background Information
For sorting parceled goods, e.g., for parcel shipments in postal operations, sorting units are used which, for example, are known from EP A 0 305 755, EP A 0 343 613 or EP A 0 619 248. Sorting units of this type, which allow an almost fully automated distribution of incoming parceled goods to various users, are provided with at least with one acceptance conveyor on which the parceled goods to be distributed are placed of at least one channeling device which has at least one delivery conveyor. The parceled goods provided to the target addresses are conveyed on the acceptance conveyor to a channeling device consistent with the target address of the parceled goods. By channeling the parceled goods to its destination, the conveyor is vacated for reloading with parceled goods by means of the channeling device. Due to the steady increase in the flow of parceled goods in the cargo area and the high investment costs involved in sorting facilities, efforts are made to achieve a high processing volume of parceled goods in these installations. Achieving a high processing volume of parceled goods is primarily contingent upon a exact positioning of individual parcels on the acceptance conveyor. If the parceled goods are not placed precisely on the acceptance conveyor by the channeling device, this can result in malfunctions which always must be remedied by manual intervention. The devices used for channeling parceled goods of varying size, shape and weight also must meet special requirements, so that the parceled goods are positioned exactly on the acceptance conveyor. This applies, in particular, when operating tipping tray installations in which the parceled goods to be channeled are placed on tipping trays. EP A 0 305 755 already determined that parceled goods, which are displaced with respect to the center line of the delivery conveyor, cannot be positioned precisely without correcting the tipping tray. This problem can be solved by various measures. As a precise placing of the parceled goods on the center line of the delivery conveyor, which would solve the problem, cannot be achieved without encountering other disadvantages, in the solutions offered by EP A 0 305 755, EP A 0 343 613 or EP A 0 619 248, the time, at which a parcel reaches the acceptance conveyor, is selected as a function of its position which is relative to the center line of the delivery conveyor. In EP A 0 305 755, a counting device is controlled by two light barriers intersecting at a specific angle, which, as a function of the position of the parceled goods, transmits the counting result as the parceled goods pass through the light barrier, as a result of which is activated a proportional delay of the otherwise static channeling process. In EP A 0 343 613, instead of delaying the start of the channeling process, this delay is achieved by using two different speeds (v.sub.o /.sqroot.2) or (v.sub.o *.sqroot.2) which temporally are set as a function of the position of the parceled goods along a light barrier which is directed parallel to the acceptance conveyor or as a function of the position of the parceled goods relative to the center line of the delivery conveyor. Instead of a starting time depending on the position of the parcel, in the second example, the time for switching between varying speeds is selected as a function of the position of the parcel, in order to achieve the required delay. The second speed (v.sub.o *.sqroot.2) is the speed with which parceled goods are channeled on the acceptance conveyor (channeling speed). The first speed (v.sub.o /.sqroot.2), which is selected to delay the parceled goods, therefore, always is lower than the channeling speed. With the known devices from EP A 0 305 755 and EP A 0 343 613, a delay is effected which is selected as a function of the lateral position of the parcel located on the delivery conveyor. This delay, which is effected independent from the position of the tipping trays provided on the acceptance conveyor, therefore, serves exclusively to balance the lateral displacement of parceled goods on the delivery conveyor.
In EP A 0 619 248, prior to accelerating the light barrier, which runs vertically along the acceptance conveyor, the parceled goods are stopped until the channeling process is initiated. The resulting displacement of the parceled goods in the direction of conveyance as a function of the lateral displacement on the delivery conveyor effects a uniform acceleration of each parcel at the acceptance conveyor.
The devices according to EP A2 0 305 755 (see page 5, lines 37-42), EP A2 0 343 613 (column 4, lines 41-57) and EP A1 0 619 248 (column 4, lines 13-25) further have in common that the parceled goods are stopped for the time during which the host computer determines the distance to the next empty tipping tray. This causes interruptions within the channeling processes which clearly reduce the processing speed of parceled goods. Delays also result from the fact that after stopping the parceled goods must accelerate to regain their channeling speed. As a result, it may happen that because of the stopping and acceleration process, an empty tipping tray may be missed. A stopping process may under certain circumstances only be avoided if an empty tipping tray is located at a suitable distance from the transfer point.